Abdul R. Khan

A thermodynamic model for liquid adsorption isotherms

Based on the principle of solution thermodynamics for liquid–solid equilibrium, a simple mathematical expression has been developed to express liquid adsorption isotherms. A weight fraction based activity coefficient model has been derived for the solid phase nonideality. The proposed model has been evaluated and compared with four other models commonly used for liquid adsorption isotherms in the literature. Systems used in this study are solute adsorption from dilute aqueous solution on various activated carbon or molecular sieve. For 14 systems at various isotherms for the temperature range 0.1–75°C and the solute concentration range of 5–26540 g/m3 for 382 data points, the proposed model predicts equilibrium concentration with an average deviation of 6%. The proposed model clearly outperforms other available methods such as vacancy solution theory, exponential model and various other modified forms of the Freundlich isotherm. The unique features of the proposed model are its simplicity, generality and accuracy over the entrie experimental concentration and temperature ranges.

Experimental Investigation of Heat and Mass Transfer in Tubular Membrane Distillation Module for Desalination

Membrane distillation is a thermally driven membrane process for seawater desalination and purification at moderate temperatures and pressures. A hydrophobic micro-porous membrane is used in this process, which separates hot and cold water, allowing water vapor to pass through; while restricting the movement of liquid water, due to its hydrophobic nature. This paper provides an experimental investigation of heat and mass transfer in tubular membrane module for water desalination. Different operating parameters have been examined to determine the mass transport mechanism of water vapor. Based on the experimental results, the effects of operating parameters on permeate flux and the heat transfer analysis have been presented and discussed in details.

Potential of membrane distillation – a comprehensive review

Membrane distillation (MD) is a recent and unique separation technology, in use in the process industry. The process of separation in MD involves the simultaneous heat and mass transfer through a hydrophobic semi permeable membrane, using thermal energy. Consequently a separation of the feed solution into two components – the permeate or product and the retentate or the return stream occurs. MD utilises low grade or alternative energy, e.g., solar energy, geothermal energy, etc., as a source and is the most cost effective separation technology. Hence the process has come to acquire the attention and interest of researchers, experimentalists and theoreticians all over the world. This article is a comprehensive review of the prominent research in the field of MD technology, including its basic principle, MD configurations, area of applications, membrane characteristics and modules, experimental studies involving the effect of main operating parameters, MD energy and economic, fouling and long-term performance.